Dual pass printing systems utilize two separate channels to produce an input image. The two channels operate independently to transfer the same information with each channel outputting half of the marking material (e.g., ink) such that the combination generates the final output. The redundancy offered by the two channels improves print quality, resulting in an output with higher optical density.
Uniformity compensation in such a system considers each of the single channels as independent primary colors and the dual pass print as an enhanced higher density primary. This concept holds for an ideal system if as in the case of an ink jet printer, every dot jetting out from a nozzle were to land in an exact location, and if the superposition theorem (e.g., optical density from ink jetted from two independent channels equals the optical density of the dual pass ink dot) were true. However since a printer operates in a real-world environment, exact dot placement is not always guaranteed due to dot-on-dot phenomenon (e.g., paper skew, web skew, hardware defects such as deviated jets or jet outs, hardware adjustments such as magnification, etc.). Thus, compensating a dual pass print by utilizing the individual channels does not provide optimum print quality.
Accordingly, a dual pass uniformity compensation mechanism is desired.